The aim of this proposal is to study the cellular and environmental mechanisms controlling the development of squamous metaplasia and the differentiation of cervical epithelial cells in vitro. The development of squamous metaplasia is important in determining the susceptibility of the cervix to neoplastic transformation and the site of infection by viruses. Presently, however, no adequate in vitro model system for studying squamous metaplasia exists. Because the development of squamous metaplasia in the rat cervix is tightly coordinated with the estrus cycle, interactions between sterioid hormones and rat cervical epithelial cells provide an excellent model for studying the differentiation of cervical cells. Recently, techniques that allow the extended monolayer culture of rat cervical epithelial cells in the absence of feeder layers have been developed. These cells offer distinct advantages for studying the differentiation of cervical cells since they are capable of extended passage and lack fibroblast feeder layers. Preliminary studies indicate that these cells have retained estrogen receptors in culture and reapond with alterations in growth and differentiation to exogenously added steroid hormones. In this grant, experiments are proposed to characterize the effects of steroid hormones, vitamin A, and extracellular matrix components on the growth and differntiation of rat cervical epithelial cells in vitro. The concentration dependency, time course, and effects of prior hormonal exposure on the responses of rat cervical epithelial cells to steroid hormones and vitamin A will be studied. The role of extracellular matrix components in determining the state of differentiation and hormonal responsiveness of the cells will be studied by growing rat cervical epithelial cells on a variety of substrata. These will include purified fibronectin, laminin, types I/III collagens, type IV collagen, and acellular amnionic membranes, and extracelular matrix produced by bovine corneal endothelial cells in vitro. The effects on differentiation will be studied with transmission and scanning electron microscopy as well as by biochemical assessment of cytokeratin polypeptide composition and cell surface glycoproteins. (M)